Re: Staff brake wheel height


Very well put. One thing that's is not obvious about "high power" geared hand brakes is you have to move the brake wheel more revolutions to have the same effect; something that I'm sure got old fast with a horizontal wheel above the car roof. The Ajax gear, and most of those that followed, were designed to take up the slack by giving the wheel one good spin and letting it freewheel until it met resistance from the brake rigging.

The other thing to note is the clearance diagram has always been a rectangle with the upper corners clipped off, in deference to the shape of arched tunnel linings and the like. Therefore the limit to car height has always been the height at the corners... there has always been extra room over the center of the car. In modern (future) times, the shape of enclosed auto racks just fills the clearance diagram.

Dennis Storzek

---In STMFC@..., <espeefan@...> wrote :


Short answer to your implied question, no.

The move to vertical wheel geared power hand brakes was the result of the shake out of various attempts to increase braking force that was needed because of the rapid increase in car weight, not car height.

Compound lever or compound pulley systems under the car and various geared contraptions attached to the brake shaft either at the bottom or top of the car end dating to the teens and before are common. With the introduction of the Ajax vertical wheel geared power hand brake in the mid '20's, quickly followed by other manufacturers, the advantages of this format won out. In all cases, these systems trade distance - the spin of the wheel - for force exerted on the brake lever at the end of the cylinder under the car.

There are many examples of what would be considered tall cars, various 50' SS autocars from the late '20's come to mind, that still used Plate A staff brakes. Well after the availability of end of car geared power hand brakes. A late example of what at the time would be considered a tall, general interchange house car using a Plate A staff brake is the GN 50000 to 50999 series DS box cars of 1937. I'm sure we could all come up with others.

Dan Smith

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